Need help making my site mobile friendly

I'm currently using the "Go" Theme for wordpress. It was the one that Godaddy recommends. The site looks great on desktop however when I look at it on mobile it looks really bad.

Example: The home page, I have a video that takes up the full screen when I first go into the desktop version

I'd like the mobile version to have a smaller version of the video but the video is cut off on the left and right edges since it wants to make it vertical instead of horizontal

I tried to edit it using Elementor but it looked even worse on elementor (I assume because its not an elementor theme) And it looked like I'd have to start from scratch

I'd rather keep this template if possible because I like it a lot for the desktop but the mobile just needs few tweaks